Humidity sensing properties of fluorine doped zinc oxide thin films

In this study, the effect of fluorine (F) doping on the humidity sensing properties of F doped zinc oxide structures was investigated. Undoped zinc oxide (ZnO) and F doped zinc oxide (FZO) nanoparticles were synthesized by sol gel method. The synthesized nanoparticles were coated on glass substrates by dip coating method. In the coating process, the glass substrates were immersed in undoped ZnO and FZO solutions and withdrawn at a rate of 25 cm/s at room temperature. Then, the thin film coated glasses are annealed in a square furnace at 500 °C for 1 h. Structural analyzes of the produced thin films were performed using X-ray diffraction and scanning electron microscopy. The thin film nanostructures were placed in the homemade system in order to investigate the humidity sensing characteristics such as relative humidity dependent resistance change, sensitivity, hysteresis, stability, response and recovery times and reproducibility. As a result, it is predicted that the FZO structures can be used in the humidity sensing applications and it is determined that the optimal F additive amount for application is 2 mol%.